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10/01/2010

CREATE ASYMMETRIC KEY (Transact-SQL)

Creates an asymmetric key in the database.

Topic link icon Transact-SQL Syntax Conventions

Syntax

CREATE ASYMMETRIC KEY Asym_Key_Name 
   [ AUTHORIZATION database_principal_name ]
   {
            [ FROM <Asym_Key_Source> ]
      |
      WITH <key_option>
   [ ENCRYPTION BY <encrypting_mechanism> ]

<Asym_Key_Source>::=
   FILE ='path_to_strong-name_file'
   |
   EXECUTABLE FILE ='path_to_executable_file'
   |
   ASSEMBLY Assembly_Name
   |
   PROVIDER Provider_Name<key_option> ::=
   ALGORITHM = <algorithm>
      |
   PROVIDER_KEY_NAME ='key_name_in_provider'
      |
      CREATION_DISPOSITION = { CREATE_NEW | OPEN_EXISTING }

<algorithm> ::=
      { RSA_512 | RSA_1024 | RSA_2048 } 

<encrypting_mechanism> ::=
    PASSWORD = 'password'

Arguments

FROM Asym_Key_Source
Specifies the source from which to load the asymmetric key pair.
AUTHORIZATION database_principal_name
Specifies the owner of the asymmetric key. The owner cannot be a role or a group. If this option is omitted, the owner will be the current user.
FILE ='path_to_strong-name_file'
Specifies the path of a strong-name file from which to load the key pair.
EXECUTABLE FILE ='path_to_executable_file'
Specifies an assembly file from which to load the public key.
ASSEMBLY Assembly_Name
Specifies the name of an assembly from which to load the public key.
ENCRYPTION BY <key_name_in_provider>
Specifies how the key is encrypted. Can be a certificate, password, or asymmetric key.
KEY_NAME ='key_name_in_provider'
Specifies the key name from the external provider. For more information about external key management, see Understanding Extensible Key Management (EKM).
CREATION_DISPOSITION = CREATE_NEW
Creates a new key on the Extensible Key Management device. PROV_KEY_NAME must be used to specify key name on the device. If a key already exists on the device the statement fails with error.
CREATION_DISPOSITION = OPEN_EXISTING
Maps a SQL Server asymmetric key to an existing Extensible Key Management key. PROV_KEY_NAME must be used to specify key name on the device. If CREATION_DISPOSITION = OPEN_EXISTING is not provided, the default is CREATE_NEW.
PASSWORD = 'password'
Specifies the password with which to encrypt the private key. If this clause is not present, the private key will be encrypted with the database master key. password is a maximum of 128 characters. password must meet the Windows password policy requirements of the computer that is running the instance of SQL Server.

Remarks

An asymmetric key is a securable entity at the database level. In its default form, this entity contains both a public key and a private key. When executed without the FROM clause, CREATE ASYMMETRIC KEY generates a new key pair. When executed with the FROM clause, CREATE ASYMMETRIC KEY imports a key pair from a file or imports a public key from an assembly.

By default, the private key is protected by the database master key. If no database master key has been created, a password is required to protect the private key. If a database master key does exist, the password is optional.

The private key can be 512, 1024, or 2048 bits long.

Permissions

Requires CREATE ASYMMETRIC KEY permission on the database. If the AUTHORIZATION clause is specified, requires IMPERSONATE permission on the database principal, or ALTER permission on the application role. Only Windows logins, SQL Server logins, and application roles can own asymmetric keys. Groups and roles cannot own asymmetric keys.

Examples

A. Creating an asymmetric key

The following example creates an asymmetric key named PacificSales09 by using the RSA_2048 algorithm, and protects the private key with a password.

CREATE ASYMMETRIC KEY PacificSales09 
    WITH ALGORITHM = RSA_2048 
    ENCRYPTION BY PASSWORD = '<enterStrongPasswordHere>'; 
GO

B. Creating an asymmetric key from a file, giving authorization to a user

The following example creates the asymmetric key PacificSales19 from a key pair stored in a file, and then authorizes user Christina to use the asymmetric key.

CREATE ASYMMETRIC KEY PacificSales19 AUTHORIZATION Christina 
    FROM FILE = 'c:\PacSales\Managers\ChristinaCerts.tmp'  
    ENCRYPTION BY PASSWORD = '<enterStrongPasswordHere>';
GO

C. Creating an asymmetric key from an EKM provider

The following example creates the asymmetric key EKM_askey1 from a key pair stored in a file. It then encrypts it using an Extensible Key Management provider called EKMProvider1, and a key on that provider called key10_user1.

CREATE ASYMMETRIC KEY EKM_askey1 
    FROM PROVIDER EKM_Provider1
    WITH 
        ALGORITHM = RSA_512, 
        CREATION_DISPOSITION = CREATE_NEW
        , PROVIDER_KEY_NAME  = 'key10_user1' ;
GO

Change History

Updated content
Corrected the syntax by removing the CERTIFICATE and ASYMMETRIC KEY options from <encrypting_mechanism>. PASSWORD is the only valid option.

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